Screw-fixed rotary connector structure for vehicles

ABSTRACT

A rotary connector  1  has a fixed case  3  for being mounted on a base  5  for a switch  4 . The fixed case  3  has a first screw insertion hole  3   a  formed open therein for insertion of a screw  6 . The screw  6  has a flange  6   a . The fixed case  3  or the base  5  has a resilient pawl  3   f  formed therein for engagement with the flange  6   a . With such structure, it is possible to screw-fix both the rotary connector and the base onto the steering column. The screw is securely kept in the rotary connector during transport and assembly by the resilient pawl.

This application is a divisional of application Ser. No. 08/711,939 filed Sep. 4, 1996, U.S. Pat. No. 5,766,019.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to rotary connector structures and, more particularly, to a screw-fixed rotary connector structure for vehicles, in which a rotary connector is screw-fixed to a base having a switch, such as a turn-signal switch, mounted thereon.

2. Description of the Prior Art

A conventional rotary connector is disclosed by Published Examined Japanese Utility Model Application No. H3-48867. According to the disclosure, the rotary connector is fixed by fastening screws onto a turn-signal switch, after inserting four screws into through-holes provided therein. In the meanwhile, the turn-signal switch is fixed by screwing onto a steering column after inserting separate three or more screws into screw holes provided therein.

In the conventional arrangement, however, the rotary connector is screw-fixed onto the base for the turn-signal switch, and the base is fixed onto the steering column by using other screws, thus increasing the number of screws as well as the number of processes of screw fastening. This results in an increased manufacturing cost. Further, since the conventional technique necessitates screw-fastening operations in very narrow locations, as in the periphery of the steering column for an automobile, it is difficult to insert screws into the screw holes in the rotary connector and the base. This difficulty often results in dropping the screws by mistake.

SUMMARY OF THE INVENTION

The present invention has been made in order to solve the above-stated problems encountered in the conventional art.

It is therefore an object of the present invention to reduce the number of screws and processes of fastening screws for simplification of screw-fastening operations in a rotary connector, by fixing the rotary connector and the turn-signal switch base using common screws attached to the rotary connector.

Additional objects, advantages and novel features of the invention will be set forth in part in the description that follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.

According to the present invention, there is provided a screw-fixed rotary connector structure for vehicles comprising a rotary connector having a first screw insertion hole formed open for insertion of a screw therethrough, a fixed case for being mounted on a base for a switch, a flange formed on the screw, and a resilient pawl formed on the fixed case or the base for engagement with the flange.

There is also provided a screw-fixed rotary connector structure for vehicles comprising a rotary connector having a first screw insertion hole opened for insertion of a screw therethrough, a fixed case for being mounted on a base for a switch, and a resilient pawl formed in the fixed case or the base for engagement with a threaded portion of the screw.

The screw-fixed rotary connector structure for vehicles of the invention may further comprise an engaging piece formed in either one of the rotary connector or the base, an engaging portion formed in the other of the rotary connector and the base for engagement with the engaging piece, and a second screw insertion hole formed open in the base for insertion of the screw, the second screw insertion hole being provided in a same axis as that of the first screw insertion hole of the rotary connector.

The flange according to the present invention may comprise a washer inserted on a threadless cylindrical portion of the screw.

The resilient pawl according to the present invention may be provided adjacent to or in the first screw insertion hole or the second screw insertion hole.

The screw according to the present invention may have a head and a flange thereof positioned in the first screw insertion hole.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more clearly appreciated as the disclosure of the invention is made with reference to the accompanying drawings. In the drawings:

FIG. 1 is an exploded perspective view showing a first embodiment of the present invention;

FIG. 2 is an essential-part enlarged sectional view showing the first embodiment of the present invention;

FIG. 3 is an exploded perspective view showing a second embodiment of the present invention;

FIG. 4 is an essential-part enlarged sectional view showing the second embodiment of the present invention;

FIG. 5 is an essential-part enlarged plan view showing a third embodiment of the present invention; and

FIG. 6 is an essential-part enlarged sectional view showing the third embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

First, explanation will be made in detail on a screw-fixed rotary connector structure for vehicles according to a preferred first embodiment of the present invention, by referring to FIGS. 1 and 2.

Reference numeral 1 represents a rotary connector which is doughnut-shaped to accommodate therein a cable reel, not shown. The rotary connector 1 is constituted by a rotatable case 2 for engagement with a steering wheel, not shown, and a fixed case 3 secured to a base 5 for mounting thereon a switch 4, such as a turn-signal switch.

The rotary case 2 has a top surface having a pair of projecting rods 2 a for engagement with blind holes, not shown, formed in the bottom face of the steering wheel, and a connector 2 b connected to one end of the cable reel accommodated within the rotary connector 1. The rotatable case 2 is rotatably engaged with the fixed case 3. The rotatable case 2 is allowed to rotate with rotation of the steering wheel through the projecting rods 2 a fitted thereto.

The fixed case 3 has a plurality of downwardly extending protuberances 3 b each formed with a first screw insertion hole 3 a. The first screw insertion holes 3 a are aligned with second screw insertion holes 5 a formed in the base 5. The fixed case 3 also has a connector 3 c which extends downward for connection to the other end of the cable reel accommodated in the rotary connector 1. By placing horizontal planar surfaces 3 d respectively formed at the lower ends of the protuberances 3 b onto ear portions 5 c of the base 5, the fixed case 3 is arranged at a desired location over the base 5 for rotation of a ratchet 4 a and a maneuver lever 4 c. The fixed case 3, together with the base 5, is fixed onto a steering column 7 by fastening screws into screw holes 7 a formed in the steering column 7.

The first screw insertion holes 3 a are each opened at a lower end of a protuberance 3 b in a center axis common to a second screw insertion hole 5 a. The first screw insertion hole 3 a and the second screw insertion hole 5 a have their inner diameters larger than an outer diameter of a threaded portion 6 b of the screw 6 so that the threaded portion 6 b is freely inserted therethrough. Incidentally, a larger diameter portion 3 i may be formed in the first screw insertion hole 3 a in a thickened planar portion 3 d so that a flange 6 a and a head 6 c of the screw 6 sink therein, in a manner similar to a first screw insertion hole 3 h of a third embodiment shown in FIG. 6, as described below.

The protuberances 3 b project downward from a plurality of areas in the periphery of the fixed case 3 to have respective planar portions 3 d at lower ends thereof formed with a first screw insertion hole 3 a. The protuberance 3 b is in a semicylindrical form so as to engage with a curvedly surfaced cutout 5 b formed in the vicinity of the second screw insertion hole 5 a.

A resilient pawl 3 f is formed on the planar portion 3 d in a manner surrounding the first screw insertion hole 3 a for engagement with the flange 6 a of the screw 6. Meanwhile, a plurality of engaging pieces 3 e are formed in the periphery of the fixed case 3 to project downward therefrom. Each engaging piece 3 e has a claw at a tip thereof for engagement with an engaging portion 5 d. A plurality of the engaging portions 5 d are formed on the top surface of the base 5. The engaging portion 5 d comes to engagement with the engaging piece 3 e upon inserting the protuberance 3 b along the cutout 5 b to register the planar portion 3 d with the ear portion 5 c, thereby engaging the rotary connector 1 with the base 5. Incidentally, the engaging piece 3 e and the engaging portion 5 d may respectively be provided in the base 5 and the fixed case 3.

The resilient pawl 3 f is an elastic piece with a claw which projects upward from the vicinity of the first screw insertion hole 3 a of the planar portion 3 d. Alternatively, a plurality of resilient pawls 3 f may be provided for each insertion hole 3 a. The resilient pawl 3 f is formed projecting such that the claw-shaped portion is engageable with the flange 6 a of the screw 6, as shown in FIG. 2. The resilient pawl 3 f has an engaging face, against which the flange 6 a abuts, provided at a height H1 with respect to the planar portion 3 d. If the distance over which the screw 6 inserted in the first screw insertion hole 3 a is movable is expressed as S1, and the thickness of the flange 6 a is expressed as T1, the height H1 of the resilient pawl 3 f can be expressed as:

H 1=S 1+T 1

The screw 6 is formed by a flanged machine screw or a flanged screw bolt, wherein a flange 6 a thereof is integrally formed, as shown in FIGS. 1 and 2. Incidentally, the screw 6 may be a machine screw having a flange 9 a comprising a washer, as shown in FIGS. 3 and 4. The flange 6 a has a diameter D1 which is slightly smaller than the distance D2 from a center axis of the first screw insertion hole 3 a to the resilient pawl 3 f so that the flange 6 a at its peripheral portion comes to engagement with the resilient pawl 3 f. The shape of the head 6 c for the screw 6 is not limited, and may be flattened or peaked.

If the thickness of the planar portion 3 d is T2, the thickness of the ear portion 5 c is T3, the length of the threaded portion 6 b threaded into a bracket 7 b is S2, and the length of the threaded portion 6 b is L1, then the following relations will stand in relation to the distance S1 over which the screw 6 inserted in the first screw insertion hole 3 a is allowed to move:

0<S1≦S2  (1)

L 1>T 2+T 3  (2)

This makes possible the prevention against falling of the threaded portion 6 b of the screw 6 out of the first screw insertion hole 3 a. Also, when the rotary connector 1 and the base 5 are fastened by screwing onto the steering column 7, the threaded portion 6 b at its tip threads into the screw hole 7 a. Incidentally, it is preferred that the length L1 of the threaded portion 6 b be determined to such a value that the threaded portion 6 b at its tip is threaded through the underside of the bracket 7 b, when the rotary connector 1 and the base 5 are fixed by the screw 6 onto the steering column 7. This enables firm fixing of the rotary connector 1 and the base 5 on the bracket 7 b.

The length L1 of the threaded portion 6 b or the length H1 of the resilient pawl 3 f is adjusted so that the threaded portion 6 b does not project at its tip from the underside of the ear portion 5 c, where the screw 6 is freely received at its threaded portion 6 b in the first screw insertion hole 3 a and the second screw insertion hole 5 a with the flange 6 a abutted against the resilient pawl 3 f. This permits the threaded portion 6 b to be sunk at its lower end in the second screw insertion hole 5 a without interfering with the bracket 7 b, when the base 5 having screws 6 and the rotary connector 1 is screwed down to the bracket 7 b. In this manner, the screwing operation is facilitated.

Reference character 3 g in FIG. 2 is a through-hole formed by insertion of a pin upon die-forming the resilient pawl 3 f. The switch 4 is constituted by a turn-signal switch or the like, which includes, for example, a ratchet 4 a, a node member 4 b, a maneuver lever 4 c, and so on. The base 5 has cutouts 5 b semi-cylindrically formed, for example, at four corners in the periphery thereof or a plurality of locations. The base 5 also has ear portions 5 c formed at respective lower ends of the cutouts 5 b, wherein the ear portion 5 c has a second screw insertion hole 5 a opened therethrough. The base 5 has a cylindrical cancellation member 8 rotatably inserted through a central portion thereof for automatically returning the maneuver lever 4 c.

The steering column 7 has brackets 7 b formed on the left and right sides. The bracket 7 b has screw holes 7 a for receiving the screws 6, and a positioning hole 7 c for fitting with a positioning projection 5 e projecting from the underside of the base 5.

The function of the first embodiment-constructed as above will next be described by referring to FIGS. 1 and 2.

To screw-fix the rotary connector 1 and the base 5 onto the steering column 7, the protuberances 3 b are first inserted respectively along the cutouts 5 b, and planar portions 3 d are pressed down to register with the ear portions 5 c. This causes alignment of the first screw insertion hole 3 a and the second screw insertion hole 5 a in their centers, integrating together the rotary connector 1 and the base 5.

Then each screw 6 is pushed so that its threaded portion 6 b is inserted into the first screw insertion hole 3 a. Upon insertion, the screw 6 comes into pressure contact at the flange 6 a with the resilient pawl 3 f to bend the same with threaded portion 6 b freely received in the first screw insertion hole 3 a and the second screw insertion hole 5 a. Thus, the screw 6 is supported with the flange 6 a and the head 6 c positioned between the resilient pawl 3 f and the planar portion 3 d. Therefore, the head 6 c of the screw 6 is allowed to move vertically within the distance S1 shown in FIG. 2.

The screw 6 will not fall out of the first and second screw insertion holes 3 a, 5 a due to abutment of the flange 6 a against the resilient pawl 3 f, unless the resilient pawl 3 f is forcibly bent outward. This makes it possible to transport the screws 6 in a state of being attached to the first and second screw insertion holes 3 a, 5 a of the rotary connector 1 before mounting the case 3 and the base 5 to the bracket 7 b. Thus, the screws are easily controlled and available during mounting.

The base 5 is then placed onto the bracket 7 b to align the second screw insertion holes 5 a to the respective screw holes 7 a while fitting the positioning projections 5 e into positioning holes 7 c. The fixed case 3 and the base 5 are screw fixed together by fastening screws 6 onto the bracket 7 b. It is noted that both the rotary connector 1 and the base 5 are screwed down to the steering column 7 at one time, thereby reducing the number of screws and processes.

Next, a screw-fixed rotary connector structure for vehicles according to a second embodiment of the present invention will be described in detail by referring to FIGS. 3 and 4. The same reference numbers are used in FIGS. 3 and 4 for denoting components of the same configuration as those of the above first embodiment, and a further explanation of those components will be omitted.

The second embodiment of the invention employs screws 9 having a washer, instead of screws 6 with a flange as in the first embodiment, and resilient pawls 5 f are provided in an ear portion 5 c of the base 5, instead of resilient pawls 3 f provided on the fixed case 3 as in the first embodiment.

Each protuberance 3 b has solely a first screw insertion hole 3 a formed in a planar portion. 3 d at the tip thereof. In a base 5, two resilient pawls 5 f are formed projecting from an ear portion 5 c in a manner surrounding a second screw insertion hole 5 a provided in the ear portion 5 c. The resilient pawls 5 f may be either singular or plural in number.

The planar portion 3 d becomes interposed between the ear portion 5 c and the resilient pawl 5 f when the protuberances 3 b are inserted along the cutouts 5 b so that the planar portions 3 d are registered with the ear portions 5 c. Alternatively, the first screw insertion hole 3 a may be provided in a manner similar to a first screw insertion hole 3 h, as shown in FIG. 6 according to the third embodiment explained below. In the alternative embodiment (FIG. 6), the first screw insertion hole 3 h has a larger diameter portion 3 i by increasing the thickness of the planar portion 3 d so as to sink therein a flange 9 a, a spring washer 9 b, and a head 9 d.

The screw 9 is formed by a machine screw with a flange 9 a formed with a washer, or a screw bolt constituted with a washer. The screw 9 is formed by roll-threading or the like, and has a spring washer 9 b and a flange 9 a formed by a plain washer. The plain washer forming the flange 9 a is freely but nonremovably received on a threadless cylindrical portion 9 c of the screw 9. Alternatively, the screw 9 may be a flanged screw integrally formed with a flange 6 a, as in the first embodiment described above. The outer diameter D3 of the flange 9 a is slightly smaller than the distance D4 between the center axis of the second screw insertion hole 5 a and the resilient pawls 5 f. This provides restriction on motion of the screw 9 by engagement at its periphery with the resilient pawl 5 f, thereby preventing the spring 9 from falling out of the second screw insertion hole 5 a. The shape of the head 9 d of the screw 9 is not limited, and may be flattened or peaked.

If the inner diameter of the flange 9 a is d1 and the outer diameter of the cylindrical portion 9 c is d2, then the outer diameter d3 of the threads in a threaded portion 9 e can be expressed as:

d3>d1>d2

By these relative dimensions, the threaded portion 9 e is prevented from falling out of the spring washer 9 b.

The resilient pawl 5 f has a claw-shaped portion formed projecting for abutment against the periphery of the flange 9 a, as shown in FIG. 4. The abutment surface of the resilient pawl 5 f against the flange 9 a is provided at a height H2 with respect to the ear portion 5 c.

If the distance over which the screw 9 inserted through the first and second screw insertion holes 3 a, 5 a is movable is S3, the thickness of the flange 9 a is T4, and the thickness of the planar portion 3 d is T5, then the height H2 of the abutment surface of the resilient pawl 5 f is expressed as:

H 2=S 3+T 4+T 5

Reference 5 g denotes a through-hole formed by a pin during die-forming of the resilient pawl 5 f.

If the thickness of the planar portion 3 d is T5, the thickness of the ear portion 5 c is T6, the thickness of the spring washer 9 b is T7, the length of the threaded portion 9 e threaded into a bracket 7 b is S4, and the length of the threadless cylindrical portion 9 c plus the threaded portion 9 e is L2, then the following expressions can be provided in relation to the distance S3 over which the screw 9 inserted in the first and second screw insertion holes 3 a, 5 a is movable:

0<S3≦S4  (1)

L 2>T 4+T 5+T 6+T 7  (2)

These relative dimensions make it possible to prevent the threaded portion 9 e of the screw 9 from falling out of the first and second screw insertion holes 3 a, 5 a. Also, when the rotary connector 1 and the base 5 are screw-fixed using screw 9 onto the steering column 7, the threaded portion 9 e at its tip is screwed into the screw hole 7 a. Thus, the rotary connector 1 and the base 5 are fixed together on the steering column 7. Preferably, the length L2 of the cylindrical portion 9 c plus the length of the threaded portion 9 e is such that the threaded portion 9 e at its tip is threaded through the underside of the bracket 7 b, as shown in FIG. 4, when the rotary connector 1 and the base 5 are screw-fixed by the screws 9 onto the steering column 7. This enables firm fixing of the rotary connector 1 and the base 5 on the bracket 7 b.

The length L2 of the cylindrical portion 9 c plus the threaded portion 9 e is adjusted so that the threaded portion 9 e does not project at the tip thereof from the underside of the ear portion 5 c, where the screw 9 is freely received at its threaded portion 9 e in the first hole 3 a and the second screw insertion hole 5 a with its flange 9 a abutted against the resilient pawls 5f. This permits the threaded portion 9 e to be sunk at its lower end in the second screw insertion hole 5 a without interfering with the bracket 7 b, when the base 5 having screws 6 and the rotary connector is screwed down to the bracket 7 b. Thus, the screwing operation is facilitated.

To screw-fix the rotary connector 1 and the base 5 for a switch 4 onto the steering column 7, the protuberances 3 b are first inserted respectively along the cutouts 5 b. During the insertion, the planar portions 3 d engage and push the respective claws of the resilient pawls 5 f to thereby spread the resilient pawls 5 f. Then, the engaging pieces 3 e each engage with the engaging portion 5 d. This causes the planar portions 3 d to be registered with the ear portions 5 c, to thereby align the first screw insertion hole 3 a and the second screw insertion hole 5 a in their centers. Thus, the fixed case 3 comes into engagement with the base 5, integrating them together.

Then each screw 9 is pushed into a first screw insertion hole 3 a. The screw 9 is freely received at its threaded portion 9 e in the first and second screw insertion holes 3 a, 5 a and the flange 9 a thereof is brought in pressure-contact with the resilient pawls 5 f to bend them. Thus, the head 9 d, flange 9 a, and the washer 9 b of the screw 9 are held between the resilient pawls 5 f and the planar portion 3 d. The flange 9 a of the screw 9 is permitted vertical movement only within the distance S3 shown in FIG. 4.

The screw 9 will not fall out of the first and second screw insertion hole 3 a, 5 a by abutment thereof against the resilient pawls 5 f, unless the resilient pawls 5 f are forcibly bent outward. This makes it possible to transport the screws 9 in a state of being attached to the first and second screw insertion holes 3 a, 5 a of the rotary connector 1 mounting with the switch 4. Thus, control of screws 9 is unnecessary.

The base 5 is then placed onto the bracket 7 b to align the second screw insertion holes 5 a to the respective screw holes 7 a while fitting the positioning projections 5 e into positioning holes 7 c. The fixed case 3 and the base 5 are screw-fixed together by fastening screws 9 onto the bracket 7 b. The rotary connector 1 and the base 5 are both screwed down to the steering column 7, thereby reducing the number of screws 9 and processes required for screw fastening.

Next, a screw-fixed rotary connector structure for vehicles according to a third embodiment of the present invention will be described in detail by referring to FIGS. 5 and 6. The same reference numbers are used to denote the same configured-elements as in the first embodiment described above, and a further explanation of these elements will be omitted.

The third embodiment of the invention has resilient pawls 31 provided in a first screw insertion hole 3 h, instead of the resilient pawls 3 f, 5 f used in the first and second embodiments, respectively. The screw 9 shown in FIGS. 5 and 6 is formed in the same shape, except that a spring washer 9 b is used with a flange 9 a formed by a plain washer freely fitted over the threadless cylindrical portion 9 c. Alternatively, the screw 9 may be configured in the same shape as the screw 6 of the first embodiment. The screw 9 at its threaded portion 9 e is engageable with resilient pawls 31 upon being pressed into a first screw insertion hole 3 h.

The first screw insertion hole 3 h is opened in a fixed case 3, and comprises a larger diameter portion 3 i and a smaller diameter portion 3 j. A stepped surface 3 k is provided between the larger diameter portion 3 i and the smaller diameter portion 3 j in the first screw insertion hole 3 h, with which the flange 9 a is to be pressure-contacted. The larger diameter portion 3 i receives a head 9 d, a spring washer 9 b, and a flange 9 a of the screw 9 to allow vertical movement of the screw 9. The smaller diameter portion 3 j has an inner wall formed with resilient pawls 31 for engagement with a threaded portion 9 e so that the screw 9 is prevented from falling out of the first screw insertion hole 3 h.

The resilient pawls 31 are each formed by a resilient piece with a claw extending upwardly from an almost central portion of the smaller diameter portion 3 j. The resilient pawls 31 may be singular or plural in number. The resilient pawl 31 has a claw-shaped portion projecting toward the inside of the smaller diameter portion 3 j. The resilient pawl 31 has gaps 3 m on the back and lateral sides thereof, and accordingly is elastically deformable backward and forward as well as rightward and leftward.

If the outer diameter of the cylindrical portion 9 c of the screw 9 is d2, the outer diameter d3 of threaded portion 9 e is d3, the inner diameter of the resilient pawls 31 is d4, and the inner diameter of the smaller diameter portion 3 j is d5, then the outer diameter d3 of the threaded portion 9 e can be expressed as follows:

d2<d4<d3<d5

As a result of these relative dimensions, the threaded portion 9 e is engageable with the resilient pawl 31.

If the distance between the stepped surface 3 k and the surface of engagement of the resilient pawl 31 is H3, the thickness of the flange 9 a is T4, the thickness of the ear portion 5 c is T6, the thickness of the spring washer 9 b is T7, and the distance over which the screw 9 placed in the fixed case 3 is movable is S5, then the length L3 of the cylindrical portion 9 c of the screw 9 can be expressed as follows:

L 3=H 3+T 4+T 7+S 5

The distance S5 over which the screw 9 attached to the fixed case 3 is movable can be expressed as follows:

S5>0

Also, if the distance from the bottom face of the fixed case 3 to the engagement surface of the resilient pawl 31 is H4, the thickness of the ear portion 5 c of the base 5 is T6, the length of the threaded portion 9 e is L4, and the distance over which the screw 9 attached to the fixed case 3 is movable is S5, then the length L3 of the cylindrical portion 9 c plus the length L4 of the threaded portion 9 e can be expressed as follows:

L 2+L 3=H 3+H 4+T 4+T 7+T 6+S 5

As a result of these relative dimensions, when the fixed case 3 and the base 5 are screw-fixed by the screws 9 onto the bracket 7 b, the threaded portion 9 e threads at its tip into the bracket 7 b, firmly fixing the fixed case and the base 3 on the steering column 7. The base 5 and the steering column 7 are preferably of the same structure as those described in the first embodiment. The base 5 is integrated with the fixed case 3 by engaging an engaging portion 5 d thereof with an engaging piece 3 e of the fixed case 3.

The third embodiment of the present invention constructed as above is formed with resilient pawls 31 for engagement with the threaded portion 9 e of the screw 9, and it is therefore possible to keep the screws 9 with the fixed case 3 and the base 5, similarly to the first and second embodiment stated above. Also, in the third embodiment, it is possible to prevent the screws 9 and resilient pawls 31 from being deformed or damaged due to external force applied thereto, because the head 9 a, the spring washer 9 b, and the flange 9 a for the screw 9, as well as the resilient pawls 31 are contained in the first screw insertion hole 3 h. Alternatively, the resilient pawls 31 may be provided in the second screw insertion hole 5 a of the base 5, offering substantially equivalent effects.

The present invention having the structure described above and shown in the drawings provides the following advantageous effects:

(1) The first aspect of the invention comprises a rotary connector having a first screw insertion hole formed open for insertion of a screw therethrough, a fixed case for being mounted on a base for a switch, a flange formed in said screw, and a resilient pawl formed in the fixed case or the base for engagement with the flange. Therefore, the screws are prevented from falling out of the first and second screw insertion holes, and kept in the rotary connector. The rotary connector can be screw-fixed together with the base onto the steering column, thereby reducing the number of screws as well as the number of processes of tightening screws. This contributes to a reduction of manufacturing costs.

(2) The second aspect of the invention comprises a rotary connector having a first screw insertion hole opened for insertion of a screw therethrough, a fixed case for being mounted on a base for a switch, and a resilient pawl formed in the fixed case or the base for engagement with a threaded portion having threads formed in the screw. Therefore, the screws are kept in the rotary connector to simplify screw-fastening operations. Also, it is possible to transport the screws together with the rotary connector and the base, thereby eliminating the problem of controlling the screws.

(3) The third aspect of the invention further comprises an engaging piece formed in either one of the rotary connector or the base, an engaging portion formed in the other of the rotary connector and the base for engagement with the engaging piece, and a second screw insertion hole formed open in the base for insertion of the screw, the second screw insertion hole being provided in a same axis as that of the first screw insertion hole. Therefore, the rotary connector and the base can be screw-fixed at one time by the use of common screws onto the steering columns. It is also possible to temporarily attach the rotary connector onto the base, thereby facilitating screw-fastening operations in screw-fixing the rotary column and the base onto the steering column.

(4) The fourth aspect of the invention includes the flange comprising a washer inserted on a threadless cylindrical portion of the screw. Therefore, the screw is kept in the rotary connector with the washer engaged with the resilient pawl, thereby preventing the screw from falling by mistake during screw-fixing the rotary connector and the base onto the steering column.

(5) The fifth aspect of the invention includes a resilient pawl provided adjacent to or in the first screw insertion hole or the second screw insertion hole. Therefore, it is possible to engage the screw with the resilient pawl.

(6) The sixth aspect of the invention includes the screw having a head and a flange thereof positioned in the first screw insertion hole. Therefore, the screw is prevented at its head, flange, washer, and resilient pawl, and so forth, from being deformed or damaged by an external force.

It will be appreciated that the present invention is not limited to the exact construction that has been described above and illustrated in the accompanying drawings, and that various modifications and changes can be made without departing from the scope and spirit thereof. It is intended that the scope of the invention only be limited by the appended claims. 

We claim:
 1. A screw-fixed rotary connector structure for vehicles comprising: a rotary connector comprising a fixed case; a base for a switch on which said fixed case is to be mounted; a first screw insertion hole, formed open in said fixed case or said base, for insertion of a screw therethrough; and a resilient pawl formed within said first screw insertion hole of said fixed case or said base for engagement with a threaded portion of said screw.
 2. A screw-fixed rotary connector structure for vehicles according to claim 1, further comprising: an engaging piece formed on either one of said rotary connector or said base; an engaging portion formed on the other of said rotary connector and said base for engagement with said engaging piece; and a second screw insertion hole formed open in said fixed case or said base for insertion of said screw, said second screw insertion hole being provided in a same axis as that of said first screw insertion hole.
 3. A screw-fixed rotary connector structure for vehicles according to claim 2, wherein said resilient pawl is provided adjacent to or in said first screw insertion hole or said second screw insertion hole.
 4. A screw-fixed rotary connector structure for vehicles according to claim 2, wherein said screw has a head and a flange thereof positioned in an enlarged portion of said first screw insertion hole.
 5. A rotary connector structure for a vehicle, comprising: a fixed case having a first screw insertion hole for receiving a mounting screw; a base having a second screw insertion hole in alignment with said first screw insertion hole for receiving said mounting screw; and a resilient pawl formed within said screw insertion hole of said fixed case or said base for engaging a threaded portion of said mounting screw to retain said mounting screw in said first screw insertion hole.
 6. The rotary connector structure according to claim 5, wherein said resilient pawl is formed on said fixed case within the first screw insertion hole.
 7. The rotary connector structure according to claim 5, wherein said resilient pawl is formed on said base within the second screw insertion hole.
 8. The rotary connector structure according to claim 5, further comprising a rotatable case connected to said fixed case for rotation relative to said fixed case, a first electrical connector mounted to said fixed case, a second electrical connector mounted to said rotatable case, and a cable reel electrically connecting said first and second electrical connectors.
 9. The rotary connector structure according to claim 8, further comprising a turn-signal switch mounted on said base.
 10. The rotary connector structure according to claim 9, wherein said first and second screw insertion holes are aligned with a screw hole formed in a steering column of the vehicle. 